Intrinsically charge-generating polymers with long-lived free carriers for efficient photon-to-hydrogen conversion

A single organic semiconductor typically struggles with inefficient intrinsic charge generation due to large binding energy (E_B ≈ 0.5 electron volts) of Frenkel excitons, particularly in narrow-bandgap organic semiconductors that exhibit near-infrared (NIR) absorption. Here, we develop double-cable polymer-based nanoparticles (NPs), enabling single-component organic photocatalysts to achieve NIR photon absorption and generate long-lived free charges simultaneously. as-DCPIC, a double-cable polymer with donor polymer (PBDB-T) as electron-donating conjugated backbones and pendent NIR acceptor (TPDIC) as the electron-deficient side chains, offers potential for self-sustained photoelectric conversion. Consequently, as-DCPIC NPs exhibit significantly enhanced hydrogen evolution performance (11.88 mmol per hour per gram) compared to pristine PBDB-T or TPDIC NPs. Transient absorption spectroscopy elucidates the effective electron-hole separation inside as-DCPIC NPs, whereas decay kinetics monitor the long-lived free carriers (109 nanoseconds) in as-DCPIC NPs. Our findings demonstrate that double-cable polymers provide a powerful platform for establishing efficient single-component organic photocatalysts to generate long-lived reactive charges.